1. Field of the Invention
This invention relates to a signal reproducing method and apparatus, a signal recording method and apparatus and a signal recording system in which the copyright information is superimposed on picture or music data and control is performed on the basis of the copyright information.
2. Description of the Related Art
There has recently been proposed a method of prohibiting unauthorized copying of picture or music data, purveyed in a stored state on a recording medium or using a network as a transmission medium, by burying the copyright information in the data by watermark processing.
The watermark processing is the processing of burying the information as noise in a perceptually non-crucial portions present im the picture or music data, that is in the non-redundant portions with respect to the music or the picture. The copyright information, buried in the picture or music data by this watermark processing, can scarcely be removed, and can be retrieved even on filtering or data compression.
Among different items of the copyright information, thus buried by watermark processing in the picture or music data, there is the copyright control information.
This copyright control information is the information specifying whether the picture or music data recorded on a recording medium or transmitted over a transmission medium is xe2x80x9ccopy freexe2x80x9d (copying possible), xe2x80x9cone copyxe2x80x9d (only one copying possible), xe2x80x9cno more copyxe2x80x9d (copying cannot be continued further) or xe2x80x9cnever copyxe2x80x9d (copying is not permitted). The reproducing device or the recording device, which has detected this copyright control information, limits reproduction or recording for the picture or music data.
Among the items of the copyright control information, there is the information indicating xe2x80x9cone copyxe2x80x9d, as described above. If the information indicating xe2x80x9cone copyxe2x80x9d is buried in the picture data etc, the user can copy from the source medium to another medium he or she owns. However, the information specifying xe2x80x9cno more copyxe2x80x9d is buried in the picture data etc recorded on the latter medium so that the user is prohibited from copying from this latter medium. Thus, the copyright control information is able to realize copying control to only one generation.
FIG. 1 shows a conventional optical disc system made up of an optical disc reproducing device 110 and an optical disc recording device 120. Referring to FIG. 1, the operation of rewriting the copyright control information from xe2x80x9cone copyxe2x80x9d to xe2x80x9cno more copyxe2x80x9d in case of copying picture data etc recorded on a source disc S to a rewritable disc RW is explained in detail.
The optical disc reproducing device 110 reproduces picture data and speech data recorded on the source disc S. In the picture data etc is buried the copyright control information reading xe2x80x9cone copyxe2x80x9d by watermark processing. The optical disc reproducing device 110 outputs; reproduced picture data etc at an output terminal 111 to send the data over a transmission medium 130 to the optical disc recording device 120.
The transmission medium 130 may be any suitable medium, such as communication cable, e.g., telephone line, bus line in a computer or a cable for AV. The picture data transmitted over the transmission medium 130 may be analog signals.
The optical disc recording device 120 receives the picture data etc transmitted over the transmission medium 130 at an input terminal 121. By a watermark (WM) detection unit 122, the optical disc recording device 120 detects the copyright control information superimposed on the picture data. Then, a watermark (WM) verification unit 123 verifies whether or not the copyright control information detected by the watermark (WM) detection unit 122 is xe2x80x9cone copyxe2x80x9d. If the optical disc recording device 120 verifies that the copyright control information reading xe2x80x9cone copyxe2x80x9d is superimposed on the input picture data, a watermark (WM) rewriting unit 124 rewrites the copyright control information superimposed on the picture data to xe2x80x9cno more copyxe2x80x9d.
The optical disc recording device 120 records the picture data, whose copyright control information has now been rewritten to xe2x80x9cno more copyxe2x80x9d, on the rewritable disc RW by a recording unit 125.
If the optical disc recording device 120 detects xe2x80x9ccopy freexe2x80x9d as the copyright control information, it allows the recording unit 125 to record directly the picture data on the rewritable disc RW, without rewriting the copyright control information. If the optical disc recording device 120 detects xe2x80x9cnever copyxe2x80x9d as the copyright control information, it terminates the recording operation.
In the conventional optical disc system 100, as described above, change of the copyright control information from xe2x80x9cone copyxe2x80x9d to xe2x80x9cno more copyxe2x80x9d is done by the RW rewriting unit 124 of the optical disc recording device 120 by way of limiting the copying to only one generation.
Meanwhile, the rewriting of the copyright control information from xe2x80x9cone copyxe2x80x9d to xe2x80x9cno more copyxe2x80x9d needs to be performed by a recording device owned by the user. However, in watermark processing, it is usually difficult to remove or rewrite the copyright control information buried in picture data etc. Although it is retained to be feasible to bury the new information by, as it were, multiple writing, on the copyright control information already buried by watermark processing in the picture data etc. This, however, leads to obstruction to the visual or auditory system, while producing undesirable interference between the new information and the old information.
For reinforcing the above-described method of burying the copyright control information in the picture data by such watermark processing, there has recently been proposed a method of writing the information termed a token or a ticket, specifying the generation limiting information indicating the number of times of possible copying or reproduction, on the so-called user area of digital data, by way of generation limitation.
If a datastream, containing digital picture data etc, is a main stream, the token or ticket is written in a sub-stream containing the control information etc of data contained in this main stream. If the picture data etc is compressed in accordance with the MPEG system and recorded on a recording medium or transmitted in this compressed form, the token or ticket is written in a header part or in the user area of this MPEG stream. In addition, the token or the ticket is written in an encrypted form for prevention of unauthorized duplication.
The token is the information specifying that one-generation copying is possible and is made up at least of one bit. If this token is written in the user area etc of the picture data etc, the user is able to copy from the source medium to an other medium in his or her possession. However, on this other recording medium, on which copying has now been made, data is recorded subject to erasure or destruction of the token. This prohibits the user from copying from this other recording medium. Therefore, this token renders it possible to control the copying to only one generation.
The ticket is digital data specifying the number of copying generations. Each time picture data etc is copied for a recording medium to another, the ticket has its value decremented to supervise the number of copying generations. Of course, this ticket is not incremented in its value. If this ticket is already written in the user area etc of the picture data etc, the user is able to copy from the recording medium carrying the recorded picture data to another recording medium in his or her possession. On the latter recording medium, on which the picture data has now been recorded, the ticket is decremented in its value by one, so that the number of possible copying generations in case of copying from this other recording medium is decremented by one. Thus, the ticket renders it possible to limit the number of generations of possible duplication.
This ticket may also be set to indicate not only the number of possible copying generations but also the number of possible reproducing generations.
If used in conjunction with the above copyright control information, the ticket denotes, by its combination, the following contents:
The processing for generation limitation of digital and speech data, in case the token or the ticket is already recorded in the user area and the copyright control information is superimposed by watermark processing on the picture or speech data, is explained specifically.
First, an optical disc system, in which picture data etc is reproduced from the source disc S, having the token recorded thereon, is explained.
FIG. 2 shows a block diagram of an authoring device 200, for generating the source disc S, and a conventional optical disc system for recording picture data etc reproduced from the source disc S on a rewritable disc RW.
The authoring device 200 includes a reproducing unit 201, for reproducing a master tape, having recorded thereon original signals for picture data and speech data for recording on the source disc S, a watermark (WM) processing unit 202, for superimposing the copyright control information on the reproduced picture data etc using watermark processing, an MPEG encoder 203, for compressing data in accordance with the MPEG system, a token generator 204 for generating the tokens, and a synthesis unit 205 for writing the generated token in a user area etc for compressed picture data.
The reproducing unit 201 reproduces the picture and speech data recorded on the master tape to send the reproduced data to the watermark (WM) processing unit 202.
The watermark (WM) processing unit 202 superimposes the copyright control information, set by the contents purveyor, on the picture or speech data, using the watermark processing. Here, the watermark (WM) processing unit 202 superimposes the information reading xe2x80x9cone copyxe2x80x9d as the copyright control information by watermark processing on the picture data. This watermark (WM) processing unit 202 sends the picture data etc to the MPEG encoder 203.
The MPEG encoder 203 compresses the picture data etc, having the copyright information superimposed thereon, by the MPEG system, to generate a compressed picture stream, which is sent to the synthesis unit 205.
The token generator 204 generates a token based on the copyright control information denoting xe2x80x9cone copyxe2x80x9d as set by the contents purveyor. The generated token is sent to the synthesis unit 205.
The synthesis unit 205 writes the token sent thereto in a user area of the MPEG stream. This synthesis unit 205 buries the copyright control information specifying xe2x80x9cone copyxe2x80x9d by watermark processing, while generating a stream in the user area of which is written the token.
The authoring device 200 writes a stream outputted by the synthesis unit 205 on the optical disc to produce source discs S distributed in large quantities among the users.
The conventional optical disc system 250 is made up of an optical disc reproducing device 260, an optical disc recording device 270 and a transmission medium 280 for analog interconnection therebetween. In this optical disc system, the optical disc reproducing device 260 reproduces picture data and speech data from the source disc S purveyed from the authoring device 200, whilst the optical disc recording device 270 records the picture and speech data reproduced by the optical disc reproducing device 260 on the rewritable disc RW. Also, in the present optical disc system 250, the optical disc reproducing device 260 and the optical disc recording device 270 are interconnected by the transmission medium 280 on which is transmitted digital data.
The optical disc reproducing device 260 expands the compressed picture data recorded on the source disc S to reproduce picture data etc. The picture data etc has the copyright control information reading xe2x80x9cone copyxe2x80x9d buried therein by watermark processing, while having the token written in its user area. The optical disc reproducing device 260 outputs reproduced picture data etc and the token at an output terminal 261 to send the data etc over the transmission medium 280 to the optical disc recording device 270.
There is no restriction to the transmission medium 280, which may, for example, be a communication cable, such as telephone line, a bus line in a computer or a cable for AV. The data transmitted on the transmission medium 280 is digital data because the token is transmitted thereon.
The optical disc recording device 270 includes an input terminal 271, a watermark (WM) detection unit 272, a token detection unit 273, a verification unit 274, a token rewriting unit 275 and a recording unit 276.
The input terminal 271 is fed with digital picture and audio data transmitted on the transmission medium 280.
The watermark (WM) detection unit 272 is fed with the input picture data etc to detect the copyright control information superimposed on these picture data etc to send the contents specified by the copyright control information to the verification unit 274.
The token detection unit 273 is fed with input picture data etc to detect the token written in the user area etc of the picture data to advise the verification unit 274 of the presence or absence of the token.
The verification unit 274 verifies whether the copyright control information specifies xe2x80x9cone copyxe2x80x9d and whether or not there exists the token. If the copyright control information for xe2x80x9cone copyxe2x80x9d is superimposed on the picture data etc and if such token exists, the verification unit 274 causes the token rewriting unit 275 to erase the token written in the user area of the picture data. At this time, the copyright control information need not be rewritten and may remain to be xe2x80x9cone copyxe2x80x9d.
The recording unit 276 is fed from the token rewriting unit 275 with picture data from which has been erased. The recording unit 276 records the supplied picture data on the rewritable disc RW.
In the present optical disc recording device 270, if xe2x80x9ccopy freexe2x80x9d is detected as the copyright control information but no token has been detected, the optical disc recording device 270 is able to terminate the recording operation.
By employing the token, the optical disc system 250 is able to perform one-generation control from xe2x80x9cone copyxe2x80x9d to xe2x80x9cno more copyxe2x80x9d without rewriting the copyright control information superimposed by watermark processing.
FIG. 3 shows an authoring device 300 for generating a source disc S, and a conventional optical disc system for recording picture data etc reproduced from the source disc S on the rewritable disc RW.
The authoring device 300 includes a reproducing unit 301 for reproducing a master tape, having recorded thereon picture and speech data for recording on the source disc S, a WM superimposition unit 302 for superimposing the copyright control information by watermark processing on the reproduced picture data etc, and an MPEG encoder 303 for compressing the data in accordance with the MPEG system. The authoring device 300 also includes a ticket generating unit 304 for generating a ticket, and a synthesis unit 305 for writing a ticket generated in the user area of, for example, the compressed picture data.
The WM superimposition unit 302 superimposes the copyright control information, as set by the contents purveyor, on the picture data or speech data. Here, the WM superimposition unit 302 superimposes the information reading xe2x80x9cone copyxe2x80x9d as the copyright control information on the picture data by watermark processing. The WM superimposition unit 302 sends these picture data etc to the MPEG encoder 303.
This MPEG encoder 303 compresses picture data etc, having the copyright a control information superimposed thereon, by the MPEG system, to generate a compressed picture stream, which is sent to the synthesis unit 305.
The ticket generating unit 304 generates a ticket for a predetermined pass, based on the pass of the ticket as set by the contents purveyor. The relation between the ticket pass and the copyright control information is that shown in Table 1 above. It is assumed that the ticket generating unit 304 has three passes designated by the contents purveyor and generates corresponding tickets. The so-generated tickets are sent to the synthesis unit 305.
This synthesis unit 305 writes the ticket sent thereto in the user area of the MPEG stream. The synthesis unit 305 buries the copyright information reading xe2x80x9cone copyxe2x80x9d by watermark processing, while generating a stream having the ticket denoting three passes written therein in the user area.
The above-described authoring device 300 writes an output stream of the synthesis unit 305 to produce source discs S distributed in large quantities among users.
A conventional optical disc system 350 includes an optical disc reproducing device 360, an optical disc recording device 370 and a transmission medium 380 for analog interconnection therebetween. In the present optical disc system, the optical disc reproducing device 360 reproduces picture and speech data from the source disc S purveyed by the authoring device 300, whilst the optical disc recording device 370 records the picture and speech data, reproduced by the optical disc reproducing device 360, on the rewritable disc RW. Also, in this optical disc system 350, the optical disc reproducing device 360 and the optical disc recording device 370 are interconnected by the transmission medium 380, on which is transmitted digital data.
The optical disc reproducing device 360 expands the compressed picture data recorded on the source disc S to reproduce picture data etc. In the picture data etc, there is buried the copyright control information reading xe2x80x9cone copyxe2x80x9d by watermark processing while the ticket specifying the three passes is written in its user area. The optical disc reproducing device 360 outputs the reproduced picture data etc and a ticket at an output terminal 361 to send the outputted data and ticket over the transmission medium 380 to the optical disc recording device 370.
There is no restriction to the transmission medium 380, which may, for example, be a communication cable, such as telephone line, a bus line in a computer or a cable for AV. The data transmitted on the transmission medium 380 is digital data because the ticket is transmitted thereon.
The optical disc recording device 370 includes an input terminal 371, a watermark (WM) detection unit 372, a ticket detection unit 373, a verification unit 374, a ticket rewriting unit 375 and a recording unit 376.
The input terminal 371 is fed with digital picture and audio data transmitted on the transmission medium 380.
The watermark (WM) detection unit 372 is fed with the input picture data etc to detect the copyright control information superimposed on these picture data etc to send the contents specified by the copyright control information to the verification unit 374.
The ticket detection unit 373 is fed with input picture data etc to detect the ticket written in the user area etc of the picture data to advise the verification unit 374 of the presence or absence of the ticket. Here, a three-pass ticket is detected.
The verification unit 374 verifies whether or not the copyright control information denotes xe2x80x9cone copyxe2x80x9d and how many there are the passes of the ticket. If the copyright control information reading xe2x80x9cone copyxe2x80x9d is superimposed on the picture data etc and there is written a three-pass ticket, the verification unit 374 causes the token rewriting unit 375 to rewrite the ticket written in the user area of the picture data to a two-pass ticket. Meanwhile, the copyright control information need not be rewritten, that is may remain to be xe2x80x9cone copyxe2x80x9d.
To the recording unit 376, there is sent picture data etc, in which is the ticket sent from the token rewriting unit 375 is changed to the two-pass ticket. The recording unit 376 records the sent picture data on the rewritable disc RW.
In the present optical disc recording device 370, if xe2x80x9cone copyxe2x80x9d is detected as the copyright control information, the recording operation is discontinued if the 0-pass, 1-pass or 2-pass ticket is detected.
In the optical disc system 350, as described above, generation management can be performed by employing a ticket, without rewriting the copyright control information superimposed by watermark processing.
However, since the above-mentioned token or ticket is digital data written in, for example, the user area of the picture data, the digital data is depleted if the analog baseband signals are outputted from the optical disc reproducing device. That is, in the case of digital data, sufficient copyright protection can be realized by having the token or the ticket contained therein by watermark processing, this merit is lost if the data is converted into the analog baseband signals.
It is therefore an object of the present invention to provide a signal reproducing method and apparatus, a signal recording method and apparatus and a signal recording system in which, even if the digital data, in which the generation limitation information specifying the number of times of possible copying or reproduction, such as a token or a ticket, is transmitted in the form of a user sub-stream of a user area etc, is converted into analog signals, it is possible to perform control based on the generation limitation information.
In one aspect, the present invention provides a signal reproducing apparatus including receiving/reproducing means for receiving or reproducing digital data transmitted via a transmission medium or recorded on a recording medium, the digital data containing a main stream and a sub-stream, the main stream being original signals having the copyright control information for copying limitation superimposed thereon by watermark processing and the sub-stream being the generation limitation information specifying the number of times of possible copying or reproduction, conversion means for converting the original signals into analog baseband signals, generation limitation information superimposition means for detecting the generation limitation information for superimposing the detected generation limitation information on the analog baseband signals, and outputting means for outputting the analog baseband signals having the generation limitation information superimposed thereon.
In this signal reproducing device, analog baseband signals, having the generation limitation information contained in the sub-stream superimposed thereon, are outputted.
In another aspect, the present invention provides a signal recording apparatus including input means supplied with analog baseband signals, the analog baseband signals being original signals having the copyright limitation information for copying limitation superimposed thereon by watermark processing and on which is superimposed the generation limitation information specifying the number of times of possible copying or reproduction, recording means for recording the analog baseband signals on the recording medium, copyright control information detection means for detecting the generation limitation information, generation limitation information detection means for detecting the generation limitation information, generation limitation information superimposition means for superimposing the generation limitation information on abs for recording, and recording limiting means for verifying, based on the copyright control information detected by the copyright control information detection means and on the generation limitation information detected by the generation limitation information detection means, whether or not the original signals are recordable on the recording medium. The recording limiting means terminates the recording operation by the recording means if the original signals are verified to be unrecordable. The recording limiting means permits the recording operation to be performed by the recording means, if the original signals are verified to be recordable, in which case the generation limitation information updated by one generation by the generation limitation information superimposing means is superimposed on the analog baseband signals.
In this signal recording device, analog baseband signals, having the generation limitation information contained in the sub-stream superimposed thereon, are received to perform copyright management.
In a further aspect, the present invention provides a signal recording system including a signal reproducing apparatus including receiving/reproducing means for receiving or reproducing digital data transmitted via a transmission medium or recorded on a recording medium, the digital data containing a main stream and a sub-stream, the main stream being original signals having the copyright control information for copying limitation superimposed thereon by watermark processing and the sub-stream being the generation limitation information specifying the number of times of possible copying or reproduction, conversion means for converting the original signals into analog baseband signals, generation limitation information superimposition means for detecting the generation limitation information for superimposing the detected generation limitation information on the analog baseband signals and outputting means for outputting the analog baseband signals having the generation limitation information superimposed thereon, and a signal recording apparatus including input means supplied with analog baseband signals from output means of the reproducing apparatus, recording means for recording the analog baseband signals on the recording medium, copyright control information detection means for detecting the generation limitation information, generation limitation information detection means for detecting the generation limitation information, second generation limitation information superimposition means for superimposing the generation limitation information on analog baseband signals for recording, and recording limiting means for verifying, based on the copyright control information detected by the copyright control information detection means and on the generation limitation information detected by the generation limitation information detection means, whether or not the original signals are recordable on the recording medium. The recording limiting means terminates the recording operation by the recording means if the original signals are verified to be unrecordable, while permitting the recording operation to be performed by the recording means if the original signals are verified to be recordable, in which case the generation limitation information updated by one generation by the second generation limitation information superimposing means is superimposed on the analog baseband signals.
In this signal recording device, analog baseband signals, having the generation limitation information contained in the sub-stream superimposed thereon, are outputted to perform copyright management.
In a further aspect, the present invention provides a signal reproducing method including receiving or reproducing digital data transmitted via a transmission medium or recorded on a recording medium, the digital data containing a main stream and a sub-stream, the main stream being original signals having the copyright control information for copying limitation superimposed thereon by watermark processing and the sub-stream being the generation limitation information specifying the number of times of possible copying or reproduction, converting the original signals into analog baseband signals, detecting the generation limitation information for superimposing the detected generation limitation information on the analog baseband signals, and outputting the analog baseband signals having the generation limitation information superimposed thereon.
In this signal recording method, analog baseband signals, having the generation limitation information contained in the sub-stream superimposed thereon, are outputted.
In a further aspect, the present invention provides a signal recording method including receiving analog baseband signals as an input, the analog baseband signals being original signals on which the copyright limitation information for copying limitation is superimposed by watermark processing and on which the generation limitation information specifying the number of times of possible copying or reproduction is superimposed, detecting the copyright control information from the analog baseband signals, detecting the generation limitation information from the analog baseband signals, and verifying, based on the copyright control information and on the generation limitation information, whether or not the original signals are recordable on a recording medium. The recording operation by the recording means is terminated if the original signals are verified to be unrecordable, while the recording operation is permitted to be performed if the original signals are verified to be recordable, with the generation limitation information updated by one generation being then superimposed on the analog baseband signals.
In this signal recording method, analog baseband signals, having the generation limitation information contained in the sub-stream superimposed thereon, are received to perform copyright management.
In yet another aspect, the present invention provides a signal recoding method including receiving or reproducing digital data transmitted via a transmission medium or recorded on a recording medium, the digital data containing a main stream and a sub-stream, the main stream being original signals having the copyright control information for copying limitation superimposed thereon by watermark processing and the sub-stream being the generation limitation information specifying the number of times of possible copying or reproduction, converting the original signals into analog baseband signals, detecting the generation limitation information and superimposing the detected generation limitation information on the analog baseband signals, transmitting the analog baseband signals having the generation limitation information superimposed thereon, receiving the analog baseband signals having the transmitted generation limitation information superimposed thereon, detecting the copyright control information from the received analog baseband signals and verifying, based on the copyright control information and on the generation limitation information, whether or not the original signals are recordable on a recording medium. The recording operation by the recording means is terminated if the original signals are verified to be unrecordable. The recording operation is permitted to be performed if the original signals are verified to be recordable, with the generation limitation information updated by one generation being then superimposed on the analog baseband signals.
In this signal recording method, analog baseband signals, having the generation limitation information contained in the sub-stream superimposed thereon, are outputted to perform copyright management of these signals.
According to the present invention, even if the digital data, in which the generation limitation information, indicating the number of times of copying or reproduction, such as a token or a ticket, is transmitted in a sub-stream, such as a user area, is converted into analog baseband signals, it is possible to output analog data that can be controlled on the basis of the generation limitation, while management concerning copyright protection can be performed on the basis of these analog baseband signals. Thus, copyright protection of the original signals can be achieved with high safety.
Also, according to the present invention, the generation limitation information can be superimposed on the analog baseband signals without obstructing or interfering with the copyright information superimposed by watermark processing.